利用netty4來實現http的伺服器，程式碼如下：

public class ApiServer {
    
    
   public static void main(String[] args) {
       int port = 8089;  
       if (args != null && args.length > 0) {  
           try {  
               port = Integer.parseInt(args[0]);  
           } catch (Exception e) {  
 
           }  
       }  
       try {
	new ApiServer().bind(port);
	System.out.println(String.format("start %s", port));
    } catch (Exception e) {
	// TODO Auto-generated catch block
	System.out.println(e.getMessage());
    }  
}
   
   public void bind(int port) throws Exception {  
       NioEventLoopGroup bossGroup = new NioEventLoopGroup(1);
	NioEventLoopGroup workerGroup = new NioEventLoopGroup();
	try {
	    ServerBootstrap boot = new ServerBootstrap();
	    boot.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).childHandler(new ChannelInitializer<Channel>() {
		@Override
		protected void initChannel(Channel ch) throws Exception {
		    // server端是接收  ，所以這裡是httprequest解碼
		    ch.pipeline().addLast(new HttpRequestDecoder());
		    // 訊息合併+最大2M，防止半包問題
		    ch.pipeline().addLast("http-aggregator", new HttpObjectAggregator(2 * 1024 * 1024));
		    //server端會返回respose 所以這裡是進行編碼
		    ch.pipeline().addLast(new HttpResponseEncoder());
		    //處理器
		    ch.pipeline().addLast(new HttpMessageHandler());
		}
	    });
	  //繫結埠，同步等待成功  
            ChannelFuture f = boot.bind(port).sync();  
            System.out.println("yes bind"+port);
            //等待服務端監聽埠關閉;  
            f.channel().closeFuture().sync();  
	}
	catch (Exception e) {
	    System.out.println(e.getMessage());
	}finally {
	    bossGroup.shutdownGracefully();
	    workerGroup.shutdownGracefully();
	}
   }

}
 

     在netty 4中，實現訊息的處理是繼承ChannelInboundHandlerAdapter 類，程式碼如下：

public class HttpMessageHandler extends ChannelInboundHandlerAdapter {
    
    private static Log  LOG=LogFactory.getLog(HttpMessageHandler.class);
  
     //進行訊息的接收
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
	//在這裡進行讀取內容
	if(msg instanceof HttpRequest){
	    HttpRequest request=(HttpRequest)msg;
	    String url =request.uri();
	    //判斷方法
	    Map<String, String> paramMap=new HashMap<String,String>();
	    if(request.method().name().equals(HttpMethod.GET.name())){
		//get 請求
		//獲取引數
		QueryStringDecoder     parmDecoder= new QueryStringDecoder(url);
		
		Map<String,List<String>>  params=parmDecoder.parameters();
		if(!params.isEmpty()){
	                params.forEach((k,v)->{
	                    v.forEach(item->{
	                	paramMap.put(k, item);
	                	System.out.println(String.format("get %s:%s", k,item));
	                    });
	                });
		}
		 String res = "I am OK";
	         write(ctx, res, null);
		
		//獲取get的引數
		
	    }else if(request.method().name().equals(HttpMethod.POST.name())){
		//post 請求
		HttpPostRequestDecoder decoder = new HttpPostRequestDecoder(request);
	            decoder.offer((HttpContent)request);

	            List<InterfaceHttpData> parmList = decoder.getBodyHttpDatas();

	            for (InterfaceHttpData parm : parmList) {

	                Attribute data = (Attribute) parm;
	                paramMap.put(data.getName(), data.getValue());
	                System.out.println(String.format("post %s_%s", data.getName(),data.getValue()));
	            }
	            String res = "I am OK";
	            write(ctx, res, null);
	    }
	}else{
	    //進行返回404
	    String res = "404";
            write(ctx, res, null);
	}
    }
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
	super.exceptionCaught(ctx, cause);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
	super.channelReadComplete(ctx);
    }
    //寫入，傳送回客戶端
    private  void write(ChannelHandlerContext ctx,String res,String contentType) {
	
	byte[] bytes=null;
		try {
		    bytes=res.getBytes("UTF-8");
		} catch (UnsupportedEncodingException e) {
		    // TODO Auto-generated catch block
		    e.printStackTrace();
		}
	FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,
    	    HttpResponseStatus.OK, Unpooled.wrappedBuffer(bytes));
	if(contentType!=null){
	    response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "text/plain");
	}else{
	    response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "text/plain");
	}
        response.headers().set(HttpHeaders.Names.CONTENT_LENGTH,
                response.content().readableBytes());
        ctx.write(response);
        ctx.flush();
    }
}